I feel like an oversight or a missed opportunity regarding Astarion was that he couldn't perform Vampire Bite on Cazador during the Ascension ritual fight. Like I understand that you can't use it on undead but with the trouble that the game established with Astarion explaining how a vampire spawn can turn into a true vampire, you would think that biting Cazador would be an exception. I think it would've been a great and ironic twist for Astarion to be able to become his own master that way as well. But oh well, I'm guessing it would've lessen the impact of certain outcomes to Astarion's questline.
Wonder how it would affect Astarion to become a true vampire. Apart from becoming very powerful, he will probably be extremely power hungry. I don't think he'll continue feeding on animals after it.
Hmm it would be really interesting. Maybe the persuasion check (to a certain outcome) would be even more difficult to pass if he were to become one.
And if he wants to remain in the party afterwards, you would be given the opportunity to keep him in check to still feed on animals or let him feed only on opponents, etc.